At a Downing Street reception for religious leaders on Tuesday, Theresa May said that people must feel able “to speak about their faith, and that absolutely includes their faith in Christ.”

“Faith in Christ?” I took an involuntary breath. Did you mean to say that Prime Minister? It sounds so, well, faithy.

She does mean it, and if Mrs May finds some way to put those words into action then it’ll do all of us good. She is not, of course, the first person of faith to occupy Number 10. As you climb the staircase in the yellow...